30 day shred is a Jillian Michael's DVD program that has 3 20-minute workouts that go in levels. You do the 1st level for 10 days, 2nd level for 10 days and 3rd level for 10 days -- they get progressively harder. She stresses that you can't take a break during the entire workout in order to get results from just 20 minutes of working out a day. The workouts are structured like this:
One 2 minute warm-up
Three 6 minute circuits (each have 3 min. of strength training, 2 min. of cardio, 1 min. of abs)
then a quick 2 minute cool down/stretch
It is actually around 22 minutes if you include the warm up and cool down.
I actually like it, and am definitely sweating by the end of it! It goes really fast. I'll keep you posted on the results if you'd like!